1. Field of the Invention
The present invention relates to a light emitting diode bulb, and in particular to a light emitting diode bulb using transmissive substrate for carrying light emitting diode dies.
2. Description of Related Art
A light emitting diode (LED) is a kind of semiconductor device, which exploits the property of direct-bandgap semiconductor material to convert electric energy into light energy efficiently and has the advantages of long service time, high stability and low power consumption and is developed to replace the traditional non-directivity light tube and incandescent lamp.
Referred is made to FIG. 1, which is a sectional view of a conventional light emitting diode (LED) bulb. The LED bulb 20 includes a housing 200, a circuit board 210, a plurality of light emitting diodes (LEDs) 226, a lamp shade 226, and a conductive connector 240. The circuit board 210 and conductive connector 240 are respectively disposed on two opposite sides of the housing 200. The circuit board 210 is of plate-shape and a surface with larger area of the circuit board 219 is attached to the housing 200. The LEDs 226 are placed on the surface with larger area of the circuit board 210 and electrically connected to the circuit board 210. The circuit board 210 provides an electric power to the LEDs 226 for lighting the LEDs 226, light emitted from the LEDs 226 transmits towards a direction opposite to the housing 200. The lamp shade 230 is assembled with the housing 220 such that the circuit board 210 and the LEDs 226 are arranged between the housing 200 and the lamp shade 230.
However, the LEDs 226 are light source having characteristic of directivity such that light emitted from the LEDs 226 just can transmit forwards (namely, the light emitted from the LEDs 226 transmits to a direction opposite to the housing 200), such that the illuminant area and lighting demand of the LED bulb 20 cannot compete with incandescent bulb for non-directivity requirement, and then usage desire of user is reduced.